Tressa Watercolors Intense Shampoo is sulfate-free shampoos that deposit just the right amount of color while cleansing, keeping hair color vibrant and true-to-tone between salon visits. Specially designed light reflecting pigments attach to porous parts of the hair, filling and adhering to the hair shaft, creating a color boost at every shampoo. Tressa Watercolors Intense Shampoo is the Most Powerful Color-Depositing Shampoo Ever Made.